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Literature summary for 2.2.1.6 extracted from

  • Vyazmensky, M.; Steinmetz, A.; Meyer, D.; Golbik, R.; Barak, Z.; Tittmann, K.; Chipman, D.M.
    Significant catalytic roles for Glu47 and Gln 110 in all four of the C-C bond-making and -breaking steps of the reactions of acetohydroxyacid synthase II (2011), Biochemistry, 50, 3250-3260.
    View publication on PubMed
Search for more literature for 2.2.1.6

Protein Variants

Protein Variants Comment Organism
E47A about 5% of wild-type activity Escherichia coli
E47Q about 5% of wild-type activity Escherichia coli
Q110A about 3% of wild-type activity Escherichia coli
Q110E about 1.5% of wild-type activity Escherichia coli
Q110H about 15% of wild-type activity Escherichia coli
Q110N about 8% of wild-type activity Escherichia coli

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
6.6
-
 pyruvate wild-type, pH 7.6, 37°C Escherichia coli
7.1
-
 pyruvate mutant E47A, pH 7.6, 37°C Escherichia coli
7.7
-
 pyruvate mutant E47Q, pH 7.6, 37°C Escherichia coli
29.5
-
 pyruvate mutant Q110N, pH 7.6, 37°C Escherichia coli
30.2
-
 pyruvate mutant Q110A, pH 7.6, 37°C Escherichia coli
40.4
-
 pyruvate mutant Q110H pH 7.6, 37°C Escherichia coli
110.6
-
 pyruvate mutant Q110E, pH 7.6, 37°C Escherichia coli

Organism

Organism UniProt Comment Textmining
Escherichia coli
-
 isoform AHAS II
-

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2 pyruvate
-
 Escherichia coli 2-acetolactate + CO2
-
 ?
2-oxobutanoate + pyruvate
-
 Escherichia coli 2-hydroxy-2-methyl-3-oxopentanoate + CO2
-
 ?
additional information residue Glu47 has a crucial catalytic role for it in the carboligation of the acceptor and the hydroxyethyl-thiamine diphosphate enamine intermediate. The Glu47-cofactor proton shuttle acts in concert with Gln110 in the carboligation. Either the transient oxyanion on the acceptor carbonyl is stabilized by H-bonding to the glutamine side chain, or carboligation involves glutamine tautomerization and the elementary reactions of addition and protonation occur in a concerted manner. Gln110 and Glu47 have global catalytic roles, being engaged in all major bond-breaking and bond-making steps. Lys159 has a minor effect on the kinetics and specificity of isoform AHAS II, far less than does Arg276,which influences the specificity for a 2-ketoacid as a second substrate. His251 has a large effect on donor substrate binding, but this effect masks any other effects of replacement of His251 Escherichia coli ?
-
 ?

Synonyms

Synonyms Comment Organism
AHAS II
-
 Escherichia coli

Turnover Number [1/s]

Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
0.4
-
 pyruvate mutant Q110E, pH 7.6, 37°C Escherichia coli
1.6
-
 pyruvate mutant E47Q, pH 7.6, 37°C Escherichia coli
1.6
-
 pyruvate mutant Q110H pH 7.6, 37°C Escherichia coli
2.7
-
 pyruvate mutant E47A, pH 7.6, 37°C Escherichia coli
2.7
-
 pyruvate mutant Q110A, pH 7.6, 37°C Escherichia coli
5.8
-
 pyruvate mutant Q110N, pH 7.6, 37°C Escherichia coli
40.3
-
 pyruvate wild-type, pH 7.6, 37°C Escherichia coli

Cofactor

Cofactor Comment Organism Structure
thiamine diphosphate residue Glu47 is involved in cofactor activation, substrate binding, and product elimination and plays a crucial catalytic role in the carboligation of the acceptor and the hydroxyethyl-thiamine diphosphate enamine intermediate. The Glu47-cofactor proton shuttle acts in concert with Gln110 in the carboligation Escherichia coli

kcat/KM [mM/s]

kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
0.004
-
 pyruvate mutant Q110E, pH 7.6, 37°C Escherichia coli
0.04
-
 pyruvate mutant Q110H pH 7.6, 37°C Escherichia coli
0.09
-
 pyruvate mutant Q110A, pH 7.6, 37°C Escherichia coli
0.2
-
 pyruvate mutant Q110N, pH 7.6, 37°C Escherichia coli
0.208
-
 pyruvate mutant E47Q, pH 7.6, 37°C Escherichia coli
0.375
-
 pyruvate mutant E47A, pH 7.6, 37°C Escherichia coli
6.1
-
 pyruvate wild-type, pH 7.6, 37°C Escherichia coli